Rio Blanco looks good

Prefeasibility work by GRD Minproc for London-based Monterrico Metals (MNA-L) at the Rio Blanco copper project in Peru suggests a net present value of US$320 million and an internal rate of return of 33%.

An open pit was designed around a reserve of 346 million tonnes grading 0.78% copper, and there is a stripping ratio of 0.7-to-1. It would produce 70,000 tonnes copper in concentrate annually from 10 million tonnes of ore over a life span of 32 years.

Byproduct credits for molybdenum were not worked into the study. Monterrico expects to have a moly resource as part of a final feasibility study.

Metallurgical tests indicate a 90-95% recovery rate in conventional flotation, which produces a 30-38% copper concentrate.

Operating costs are estimated at US55 per lb. (US$1,220 per tonne) over the life of the mine, with early production from higher-grade zones bringing costs down and copper production up in the first five years of operation. Annual production averages 103,000 tonnes copper in the first five years.

Capital costs of US$191 million would be paid back in three years.